Improvement in files



FFICE.

JOHN HOSMER CLARK, OF WASHINGTON, DISTRICT OF COLUMBIA.

IMPROVEMENT IN FILES.

Specification forming part of Letters Patent N0. 105,044, dated July 5, 1870- To alt whom it may concern:

Beit known that I, JOHN HosMEn CLARK, of the city and county of Washington, and District of Columbia, have invented a certain Improvement in Steel-Plate Files.

My invention relates to that class of iles which have their teeth formed of separate plates mounted upon a bar, and secured in po- 1sition by means of end screws or their equivaents.

My invention consists in certain novel arrangements by means of which the several plates, having` been ground in mass upon a grindstone, may be reversed in position lwithout removing them from the bar, thus transforming a smooth or safe77 surface into a cutting-surface in an 'expeditious and truly practicable manner 5 and I do hereby declare that the following specification, taken in connection with the drawing furnished and forming a part of the same, is a clear, true, and exact description thereof.

Figure l represents one of my improved files in perspective, showing the sharp or cutting side and edge. Fig. 2 represents the same, showing the safe or smooth side and edge. Fig. 3 represents the same with the handle and a portion of the cutting-plates removed. Fig. 4 represents one of the steel cutting-plates.

A is the handle of the le. tending from end to end of the file. base-block. D is the end block.

The space on the bar betweenthe inner ends of the base and end blocks is filled with thin plates of inely-tempered steel. They are in the form of a parallelogram, and have in their centers eyes of corresponding form.

The bar B is round at the portion inclosed by the handle, and also at its opposite end. Both ends are provided with a screw-thread cut thereon, to which suitable nuts are fitted. That portion of the bar between the round portions described is rectangular, and corresponding in form to the eyes in the plates, but is slightly smaller, so that the plates will readily slide thereon, and admit of their being slanted backward and forward.

B is a bar ex- C is the rlhe base and end blocks C and D have theirA outer ends faced off square. Their inner ends .have faces cut with angles oblique both to their sides and edges, and corresponding closely one with the other. When placed with their inner ends together, the two faces should match, and, while in closecontact, preserve continuously the straight lines of the sides and edges.

The four edges of all the plates are beveled by grinding after being placed on the bar. These beveled edges on each plate incline outward from that surface which is nearest the handle, and thus, in virtue of the divergent direction of said beveled surfaces, which impart to the plates their cutting-edges, and of the double Obliquity of the inner faces of the blocks C and D, when the plates are placed upon the bar with the base and end blocks adj usted, and the nuts turned up tight to force all the plates to assume an angle corresponding to the inner faces of the blocks, the le then presents one edge and one side smooth or safe, while the other edge and side present a cuttingsurface.

The cuttingedges of the teeth are on that side and edge of the le in which the corner angles incline toward the handle, while the incline of the plates at the corner of the safe edge and side is toward the opposite end. When inclined as last described, the smooth edge and side may be placed upon a grndstone, and in proportion as the plane surface is ground smooth, so is each tooth or edge sharpened.

When the cutting side and edge require sharpening it is only necessary to remove the nuts at the ends of the bar, withdraw the base and end blocks, turn them half round, replace them, and readjust the nuts. The side and edge beforesmooth would then be the cuttingsurfaces, while the last cutting-surfaces would be ready for grinding.

I am aware that plate-files have been heretofore made, and that by the use of angularfaced head-blocks a safe side and edge capable of being ground, and also a cutting side and edge, are produced. In such cases, however, the base-block bar, and shank were in one piece, While the end block was substantially the same as that shown by me. The plates were closely fitted to the bar. With such files it was impracticable to change from a safe to a cutting-surface without rst removing all the plates from the bar, and then re- 'f series of cutting-plates mounted upon the bar placing them with edges reversed.

rlhe object of my improvement is to accomplish this change by the simple reversal of th base and end blocks.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- The combination of the reversible base and end blocks C and D, provided with corresponding duplex angular inner faces, and the B, held securely in position by suitable compression devices, all arranged to admit of the alternate changing of the safe and cutting sur` faces Without the removal of the plates from the bar, as and for the purposes specified.

JOHN HOSMER CLARK.

Witnesses:

PHIL. F. LARNER, FRANK A. J AcKsoN. 

